Amino-aroylamino-benzoic acid and process of making it



are by weight, illustrate but do not Patented Aug. 3, 1937 AMINO-AROYLAMINO-BENZOIC ACID AND PROCESS OF MAK NG IT Francis Leslie Rose, Blackley, Manchester, England, assignor to Imperial Chemical Industries Limited, a corporation of Great Britain No Drawing. Application October 28, 1935, Serial No. 47,199. In Great 3 Claims.

This invention relates to new compounds being 2-amino-5-aroylamino-benzoic acids, and to processes of making them.

An object of the invention is to produce new and useful compounds and to produce them by economically and technically satisfactory methods. Other objects of the invention will be in part apparent and in part more fully hereinafter set forth.

The objects of the invention are accomplished, generally speaking, by making 2-amino-5-aroylamino-benzoic acids and by the processes more fully hereinafter set forth. The objects of the invention are also accomplished in some degree by the products and processes more fully hereinafter set forth.

The new products may be made in the preferred process by nitrating m-aroylamino-benzoic acid and subsequently reducing the nitro group to an amino group, or in an alternative process by aroylating 3-amino-G-acetaminobenzoic acid and thereafter converting the acetamino group to an amino group, e. g. by hydrolysis. The preferred method has the advantages of requiring fewer stages in the process of manufacture and of utilizing commercially available raw materials.

The new intermediates are useful for making azo dyestuffs.

The following in which the parts limit the inexamples,

vention.

Example I 24.1 parts of S-benzoylaminobenzoic acid were dissolved in 135 parts of concentrated sulfuric during the addition, and was raised to and main- 55 cream colored powder readily soluble tained at 20 C. for two hours. The reaction mass was poured on 500 parts of crushed ice, and a solid substance which precipitated on standing over night, was filtered off and washed with water. This solid substance was the crude nitro compound. It was further purified by dissolving in 250 parts of water, making the solution just alkaline to litmus paper by adding calcined sodium carbonate, and salting out. The sodium salt was dissolved in 250 parts of water, and the free acid was formed and precipitated by adding hydrochloric acid. The washed and dried product, 2-nitro-5-benzoylaminobenzoic acid, is a in alcohol Britain October 30,

and slightly soluble in hot water. It is represented by the formula:

until most of the amino acid had precipitated.

More precipitate was obtained by cooling and diminishing the acidity of the suspension. The product obtained was 2-amino-5-benzoylaminobenzoic acid. It was filtered off, washed with water, and dried; It is represented by the formula:

COOH

C ONE 2-amino-5-benzoylaminobenzoic acid was a white powder melting at 245-250 C., and sparingly soluble in water, cold dilute mineral acids, benzene, or acetone. It dissolves readily in hot ethyl alcohol.

Example II 29.8 parts of 3-benzoylamino G-acetaminobenzoic acid, made by treating S-amino-G-acetaminob-enzo-ic acid with benz'o-yl chloride in aqueous suspension in acetate, were dissolved in 300 parts of water containing 22 parts of aqueous caustic soda (32%). The solution was boiled under a reflux condenser for two hours. 2-amino-5-benzoylaminobenzoic acid identical with the product obtained in Example I was obtained as a precipitate by adding concentrated hydrochloric acid to the cooled solution until it was just acid to blue litmus paper.

As many apparently widely difierent embodiments of this invention may be made without the presence of sodium departing from the s to be understood that I specific in the I clai 1. 2-amino-5-aro parts of 3-benzoy1amin embodiments e process which pirit and scope thereof, it is do not limit myself to the thereof except as defined appended claims.

ylamino-benzoic acid.

comprises dissolving 24.1 obenzoic acid in sulfuric acid, nitrating it, separating out the nitrated roduct by pouring over ice, purifying it, and reducing the nitro group to amino.

3. The process which comprises nitrating 3- benzoylaminobenzoic acid and reducing the nitro 5 group of the nitro benzoylaminobenzoic acid to FRANCIS LESLIE ROSE. 

